Applicant hereby claims foreign priority under 35 U.S.C. xc2xa7119 from German Application No. 10129003.9, filed Jun. 16, 2001, the disclosure of which is herein incorporated by reference.
The invention relates to seal system for covers or flange couplings that are under high pressure.
For covers or flange couplings there are a plurality of potential seal types. In high pressure applications, one type has been developed in which a somewhat raised rounded knife edge upon tightening on one side produces a small deformation in the plane surface of the opposite side. This elastic-plastic working in the seal region guarantees consistently a reliable sealing of gases and fluids in a high pressure region whereby pressures of up to more than 1,000 bar are common. The connection can very often be unfastened and again closed without having to re-work the seal region unless it should happen that mechanical damage should be found. Mechanical damage or chemical attack requires as described a re-working in the seal region. On these grounds a seal exchangeable on the spot would employ the same principles in which a metal ring inlayed in a half round groove after tightening the threaded connection is fully embedded with a minimal excess projecting against the basic cover surface. This excess forms the raised rounded knife edge of the above described high pressure seal.
A disadvantage of this type of seal ring is the disassembly. Due to the pressure process, the ring rests so firmly in the grove that it must be chiseled out of its position. The residue can then be pulled out with suitable tongs. However the chisel process just described possesses a significant danger that the groove or alternatively the surrounding surface will be damaged. Then the supplemental work, for example for a large cover of a diaphragm compressor, will be a very expensive matter.
In Swiss patent CH 374,256, U.S. Pat. No. 4,410,186 and German patent DD 296,333 A5 and British patent GB 1,009,221 apparatuses are described with a groove having an inlaid seal body wherein the base of the groove remains connected with the surroundings by means of a boring which, however, only serves the purpose of leakage control for the inserted seal body.
In German patent DE 848,128 C and British patent GB 950,440 the channels, which define the bottom of the groove serve only as the feed means for a pressurizing medium in order to produce the pre-stressing of the seal necessary for the sealing function.
Furthermore there are devices, described in German patents DE 106,534C, DE 1,959,561B and DE 1,888,462U, in which a comparable ring embedded in a groove is provided, however, without any type of backside groove or channels with borings.
An object of the invention is the provision of a seal which combines the mentioned advantages of the prior art, however, also better and without the risk of damage as can again be demonstrated.
This object is achieved by means of a concentric half round groove encircling the cover with a very small relief groove in the bottom of the groove. A small pressure feeding bore discharges into the relief groove from the backside of the cover. A metal ring, after insertion in the half round groove and after pre-stressing by the screw connection or bolt connections, completely fills the half round groove and only a small portion of the relief groove, and accordingly forms a minimal excess at the basic cover surface which together with the opposite flange surface forms a high pressure seal.